Acetic acid, azido-, ethyl ester → Ethyl 2-azido-3-(5-bromothiophen-2-yl)acrylate

A solution of sodium (2.76 g, 120 mmol) in absolute EtOH (120 mL) was cooled in an ice-bath and a mixture of 5-bromo-2-formylthiophene (5.73 g, 30 mmol) and ethyl azidoacetate (15.49 g, 120 mmol) was added dropwise during 30 min period. The bath was removed and the reaction mixture was stirred at room temperature for another 30 min. A cold solution of saturated aqueous NH4Cl solution (100 mL) was added and the resulting solution was extracted with diethyl ether (3×100 mL) and the combined organic layers were washed with brine (200 mL), dried over Na2SO4. After removing diethyl ether under reduced pressure, the crude product was purified by column chromatography (EtOAc/Hexane: 1/50) to give acrylate 60 (3.81 g, 42%) as a light yellow solid.